Cluster of inclined structures

ABSTRACT

The present invention involves both the geometrical specification of a structure and positioning the structure in the cluster layout to achieve rapid heating/cooling as a medium transverses through them, and with little pressure drop penalty.

PRIORITY

The present invention claims the benefit of U.S. Provisional ApplicationNo. 61/820,158 filed May 6, 2013.

FIELD OF THE INVENTION

The present invention involves both the geometrical specification of astructure and positioning of the structure in the cluster layout toachieve rapid heating/cooling as a medium transverses through them, withlittle pressure drop penalty.

BACKGROUND OF THE INVENTION

This invention builds upon prior art: PCT/SG2010/000169—An Enhanced HeatSink, but encompasses a wider range of applications and configurations.

PCT/SG2010/000169 description: A heat sink device for dissipating heatfrom an electronic component mounted there to, the device comprising: aninlet for receiving a fluid; an outlet for venting said fluid; a heatdissipation zone intermediate the inlet and outlet; said zone includinga plurality of transverse channels and a plurality of oblique channelsextending between adjacent transverse channels; wherein said oblique andtransverse channels define a fluid path for said fluid from the inlet tothe outlet.

The prior art clearly states itself as a ‘heat sink device’. Thisinvention is not limited to a ‘heat sink device’ and its purpose of heatdissipation. This invention includes any cluster of inclined objectsarranged for the purpose of enhanced heat transfer or disruption ofthermal or hydrodynamic boundary layers, such as battery cooling andwind distribution in a cluster of buildings.

The purpose of the prior art is the dissipation of heat from a secondary‘electronic component’ mounted on the prior art invention. Thisinvention is not limited to the case of heat dissipation from asecondary ‘electronic component’. The secondary component can benon-electronic in nature such as in the case of engine cooling. In somecases, the primary objective of heat transfer can be the inclinedobjects themselves, such as in the case of battery cooling presented inthe summary of invention.

The prior art comprises of inlet and outlet vents. The invention doesnot limit itself to configurations and applications involving an inletand outlet vent. Similarly, the invention includes cases, in which thecluster of inclined structures is not enclosed as otherwise depicted bythe prior art.

The prior art makes claims for angles of inclinations from 20 to 45degrees. This invention expands the angles of inclinations to 0 to 90degrees.

The prior art only makes claims for flow within the transverse and/oroblique channels when Reynolds Number is less than 2300. This inventionis not limited to any range of Reynolds Number.

The prior art only makes claims for structures with sharp edges. Thisinvention also includes inclined structures with rounded edges.

SUMMARY OF THE INVENTION

The present invention involves both the geometrical specification of astructure and positioning of the structure in the cluster layout toachieve rapid heating/cooling as a medium transverses through them, andwith little pressure drop penalty. The geometry of each structure andthe positioning of each structure in the cluster is depicted in FIGS. 1and 2.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of the inclined structures of the presentinvention arranged in a cluster.

FIG. 2 is a plan view of the cluster of the present invention showingfluid flow pattern.

FIG. 3 illustrates geometric parameters of the cluster of the presentinvention.

FIG. 4 illustrates inclined structures of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention involves both the geometrical specification of astructure and the positioning of the structure in the cluster layout toachieve rapid heating/cooling as a medium transverses through them, withlittle pressure drop penalty. The geometry of each structure and thepositioning of each structure in the cluster is depicted in FIGS. 1 and2.

As seen from FIG. 2, the fluid flow comprises two channel streams,namely the mainstream flow, which is parallel to the direction ofmainstream flow, and diverted flow, which is diverted from themainstream flow by an inclined slope of between 0 to 90 degrees. Thediverted flows cause the boundary layers at the leading edge of eachstructure to be re-initialized, thus reducing boundary layer thickness.The re-initialization causes the mainstream flow to maintain a thermallydeveloping state throughout the channel, resulting in better heattransfer. The diverted channels divert a small fraction of flow awayfrom the main channel, thus improving fluid mixing. Improved fluidmixing further enhances heat transfer. In addition, a pressure recoveryeffect is also noticed in the diverted channel, which minimizes thepressure drop penalty for the increased heat transfer.

Compared with a conventional arrangement of prismatic structures,inclined structures and its arrangement in the aforementioned clusterlayout have much higher heat transfer capacity between the structuresand the cooling medium. This improved efficiency in heat transfer can bekey enablers for the successful development of electricvehicles/hybrid-electric vehicles with or without fast chargingcapabilities. This is because the efficiency and life-cycle of batteriesare dependant on their temperature. The cooling medium in thisapplication includes but is not limited to natural airflow andinduced-air flow by a fan. Other applications of this invention includethe geometrical optimization and positioning of buildings, the walls ofbuildings or racks in data centers for improved airflow for cooling.

The enhancement in heat transfer in the present invention was verifiedthrough a benchmarking study conducted using computational fluiddynamics (CFD) analysis, for cases in which (1) normal prismaticstructures and the instant invention—(2) inclined structures that areplaced in a cluster of 4 by 4 in an enclosure. The volume of both thenormal prismatic and inclined structures were kept the same for a faircomparison. However the inclined shape of the structure results in a22.86% increase in total volume occuppied by the cluster. The detailedgeometric parameters are listed in Table 1. FIG. 3 also shows thegeometric parameters in the clusters. The air of temperature 20° C.flows into the enclosure with uniform velocity of 0.1068 m/s and exitsat the other end with an environment pressure of 101325 Pa. A volumetricheat flux of 17771 W/m³ was supplied to each structure to give 40W/structure and a thermal conductivity of 3.4 W/m²K and volumetricspecific heat capacity of 12.17 J/m³K were applied to the structures.

TABLE 1 Geometric parameters of the structures Space Space betweenbetween Structure Structure Additional Structure Structure Structure inx- in y- Inclined Volume Structure Width Length Height directiondirection Angle of Cluster Shape (mm) (mm) (mm) (mm) (mm) (°) (%) Normal80.5 116.5 240 8 6 — — Prismatic Inclined 80.5 228 240 8 6 35.66 22.86

Table 2 shows the comparison of temperature data between the two cases:(1) normal prismatic structures and (2) inclined structures.

TABLE 2 Temperature and Pressure data of (1) Normal Prismatic and (2)Inclined Structures Bulk Pressure Minimum Maximum Temper- Average DropTemper- Temper- ature Temper- across Structure ature ature Differenceature enclosure Shape (° C.) (° C.) (° C.) (° C.) (Pa) Normal 32.02 7946.98 64.88 15.9 Prismatic Inclined 27.25 71.26 44.01 54.04 19.1

The inclined structures cluster has a Bulk Average Temperature of morethan 10° C. lower than that of the normal prismatic structures cluster,and also displays a lower Maximum Temperature and TemperatureDifference. This is at the expense of a 20% increase in pressure dropand a 22.86% of additional volume required. However, with a largercluster, the additional volume will become a smaller proportion of totalvolume. Pressure drop proportion will also decrease due to the reductionin proportion of additional flow length.

Even though the value for the angle of inclination in this simulation is35.66 degrees, the range of angles where there will be cooling benefitsis between 0 to 90 degrees. This invention also covers varied designs ofthe structures. One variation of this invention is shown in FIG. 4,where the edges of the structures are rounded while the mainstreamchannels, diverted channels and inclined slopes of the structures aremaintained.

Optimization of the incline angle depends on several factors—heatdissipation and pressure drop requirements, type of cooling medium,space required between the structures. We have however determined 35.66degrees to be one of the optimal configurations for use of air as afluid for the purpose of cooling battery cells.

The present invention contemplates the optimization of dimensions forthe mainstream and diverted channels, dimensions for inclinedstructures, range of incline angle, flow velocity of cooling medium anddimensions of the whole cluster.

We claim:
 1. An array structure and its positioning in the clusterlayout comprising one or more shape edges arranged to achieve rapidheating/cooling as a medium transverses through them, and with littlepressure drop penalty.
 2. The array structure according to claim 1,wherein said each shape edges are positioned at an angle to thetransverse edge in the range 1° to 89°.
 3. The array structure accordingto claim 1, wherein a cross-sectional area of any one of sloped gaps isless than a cross-section area of transverse gaps between which thesloped channel extends.
 4. The array structure according to claim 1,wherein elements of a heat dissipation zone separating one or morechannels are heat dissipation sources.
 5. The array structure accordingto claim 1, wherein sloped gaps are uniformly spaced from each otherwithin a heat dissipation zone.
 6. The array structure of claim 1capable of use as a heat sink device, wherein oblique channels areuniformly spaced from each other within a heat dissipation zone.
 7. Thearray structure of claim 1 capable of use as a heat sink device, furthercomprising at least one heat concentration zone within a heatdissipation zone, such that spacing of oblique channels within the atleast one heat concentration zone is less than the spacing of theoblique channels within a remaining portion of the heat dissipationzone.
 8. The array structure of claim 1 capable of use as a heat sinkdevice, further comprising at least one heat concentration zone withinthe heat dissipation zone, such that spacing of transverse channelswithin the at least one heat concentration zone is less than the spacingof the transverse channels within a remaining portion of the heatdissipation zone.
 9. The array structure of claim 8 capable of use as aheat sink device, further comprising a plurality of heat concentrationzones within the heat dissipation zone.